This invention relates to printer systems generally, and particularly to timely positioning of print media such as print drums, print disks, and print bands for printing.
Generally, the print medium includes a variety of uniformly arranged characters, and has a corresponding number of timing marks (e.g., vertical bars, slits, etc.) aligned with the characters. Some systems use one sensor with one set of marks to determine positions of the individual characters, others use two sensors (i.e., different sensors with different marks) to determine the positions of individual characters and the velocity of the medium (e.g., the rate of movement of the medium relative to a print head or other sensor).
One such system is described, for example, in U.S. Pat. No. 2,919,967 entitled "High-Speed Electrostatic Alphanumerical Printer" issued Jan. 5, 1960 to F. A. Schwertz. Another such system is described in U.S. Pat. No. 4,665,820 entitled "Print Band Timing Mark Detector", issued May 19, 1987 to W. Chapman. A third such system is described in U.S. Pat. No. 4,815,873 entitled "Initializing Method For Printing Type Rings in Printer", issued Mar. 28, 1989 to F. Hori. A common concern with many such prior art systems is design complexity, with its attendant lower reliability, less compactness, and increased cost of manufacture.
What is needed and would be useful, therefore, is a system (apparatus) of less design complexity, which would be reliable, compact, and cost less to manufacture.